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  • JOURNAL ARTICLE
    Imtiaz SA, Mardell J, Saremi-Yarahmadi S, Rodriguez-Villegas Eet al., 2016,

    ECG artefact identification and removal in mHealth systems for continuous patient monitoring.

    , Healthc Technol Lett, Vol: 3, Pages: 171-176

    Continuous patient monitoring systems acquire enormous amounts of data that is either manually analysed by doctors or automatically processed using intelligent algorithms. Sections of data acquired over long period of time can be corrupted with artefacts due to patient movement, sensor placement and interference from other sources. Owing to the large volume of data these artefacts need to be automatically identified so that the analysis systems and doctors are aware of them while making medical diagnosis. Three important factors are explored that must be considered and quantified for the design and evaluation of automatic artefact identification algorithms: signal quality, interpretation quality and computational complexity. The first two are useful to determine the effectiveness of an algorithm, whereas the third is particularly vital in mHealth systems where computational resources are heavily constrained. A series of artefact identification and filtering algorithms are then presented focusing on the electrocardiography data. These algorithms are quantified using the three metrics to demonstrate how different algorithms can be evaluated and compared to select the best ones for a given wireless sensor network.

  • CONFERENCE PAPER
    Patrick KCA, Imtiaz SA, Bowyer S, Rodriguez-Villegas Eet al., 2016,

    An algorithm for automatic detection of drowsiness for use in wearable EEG systems

    , Pages: 3523-3526, ISSN: 1557-170X

    © 2016 IEEE.Lack of proper restorative sleep can induce sleepiness at odd hours making a person drowsy. This onset of drowsiness can be detrimental for the individual in a number of ways if it happens at an unwanted time. For example, drowsiness while driving a vehicle or operating heavy machinery poses a threat to the safety and wellbeing of individuals as well as those around them. Timely detection of drowsiness can prevent the occurrence of unfortunate accidents thereby improving road and work environment safety. In this paper, by analyzing the electroencephalographic (EEG) signals of human subjects in the frequency domain, several features across different EEG channels are explored. Of these, three features are identified to have a strong correlation with drowsiness. A weighted sum of these defining features, extracted from a single EEG channel, is then used with a simple classifier to automatically separate the state of wakefulness from drowsiness. The proposed algorithm resulted in drowsiness detection sensitivity of 85% and specificity of 93%.

  • JOURNAL ARTICLE
    Pramono RXA, Imtiaz SA, Rodriguez-Villegas E, 2016,

    A Cough-Based Algorithm for Automatic Diagnosis of Pertussis

    , PLOS ONE, Vol: 11, ISSN: 1932-6203
  • JOURNAL ARTICLE
    Chen G, Imtiaz SA, Aguilar-Pelaez E, Rodriguez-Villegas Eet al., 2015,

    Algorithm for heart rate extraction in a novel wearable acoustic sensor.

    , Healthc Technol Lett, Vol: 2, Pages: 28-33

    Phonocardiography is a widely used method of listening to the heart sounds and indicating the presence of cardiac abnormalities. Each heart cycle consists of two major sounds - S1 and S2 - that can be used to determine the heart rate. The conventional method of acoustic signal acquisition involves placing the sound sensor at the chest where this sound is most audible. Presented is a novel algorithm for the detection of S1 and S2 heart sounds and the use of them to extract the heart rate from signals acquired by a small sensor placed at the neck. This algorithm achieves an accuracy of 90.73 and 90.69%, with respect to heart rate value provided by two commercial devices, evaluated on more than 38 h of data acquired from ten different subjects during sleep in a pilot clinical study. This is the largest dataset for acoustic heart sound classification and heart rate extraction in the literature to date. The algorithm in this study used signals from a sensor designed to monitor breathing. This shows that the same sensor and signal can be used to monitor both breathing and heart rate, making it highly useful for long-term wearable vital signs monitoring.

  • JOURNAL ARTICLE
    Imtiaz SA, Logesparan L, Rodriguez-Villegas E, 2015,

    Performance-Power Consumption Tradeoff in Wearable Epilepsy Monitoring Systems

    , IEEE JOURNAL OF BIOMEDICAL AND HEALTH INFORMATICS, Vol: 19, Pages: 1019-1028, ISSN: 2168-2194
  • CONFERENCE PAPER
    Imtiaz SA, Rodriguez-Villegas E, 2015,

    An Open-source Toolbox For Standardized Use Of PhysioNet Sleep EDF Expanded Database

    , 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Publisher: IEEE, Pages: 6014-6017, ISSN: 1557-170X
  • CONFERENCE PAPER
    Imtiaz SA, Rodriguez-Villegas E, 2015,

    Automatic Sleep Staging Using State Machine-controlled Decision Trees

    , 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Publisher: IEEE, Pages: 378-381, ISSN: 1557-170X
  • JOURNAL ARTICLE
    Casson AJ, Rodriguez-Villegas E, 2014,

    Nanowatt multi-scale continuous wavelet transform chip

    , ELECTRONICS LETTERS, Vol: 50, Pages: 153-154, ISSN: 0013-5194
  • CONFERENCE PAPER
    Hizon JRE, Rodriguez-Villegas E, 2014,

    A Reconfigurable FGMOS based OTA-C Filter

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2093-2096, ISSN: 0271-4302
  • JOURNAL ARTICLE
    Imtiaz SA, Casson AJ, Rodriguez-Villegas E, 2014,

    Compression in Wearable Sensor Nodes: Impacts of Node Topology

    , IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 61, Pages: 1080-1090, ISSN: 0018-9294
  • JOURNAL ARTICLE
    Imtiaz SA, Rodriguez-Villegas E, 2014,

    A low computational cost algorithm for REM sleep detection using single channel EEG.

    , Ann Biomed Eng, Vol: 42, Pages: 2344-2359

    The push towards low-power and wearable sleep systems requires using minimum number of recording channels to enhance battery life, keep processing load small and be more comfortable for the user. Since most sleep stages can be identified using EEG traces, enormous power savings could be achieved by using a single channel of EEG. However, detection of REM sleep from one channel EEG is challenging due to its electroencephalographic similarities with N1 and Wake stages. In this paper we investigate a novel feature in sleep EEG that demonstrates high discriminatory ability for detecting REM phases. We then use this feature, that is based on spectral edge frequency (SEF) in the 8-16 Hz frequency band, together with the absolute power and the relative power of the signal, to develop a simple REM detection algorithm. We evaluate the performance of this proposed algorithm with overnight single channel EEG recordings of 5 training and 15 independent test subjects. Our algorithm achieved sensitivity of 83%, specificity of 89% and selectivity of 61% on a test database consisting of 2221 REM epochs. It also achieved sensitivity and selectivity of 81 and 75% on PhysioNet Sleep-EDF database consisting of 8 subjects. These results demonstrate that SEF can be a useful feature for automatic detection of REM stages of sleep from a single channel EEG.

  • CONFERENCE PAPER
    Imtiaz SA, Rodriguez-Villegas E, 2014,

    Recommendations for Performance Assessment of Automatic Sleep Staging Algorithms

    , 36th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC), Publisher: IEEE, Pages: 5044-5047, ISSN: 1557-170X
  • CONFERENCE PAPER
    Imtiaz SA, Rodriguez-Villegas E, 2014,

    Evaluating the use of line length for automatic sleep spindle detection

    , 36th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC), Publisher: IEEE, Pages: 5024-5027, ISSN: 1557-170X
  • JOURNAL ARTICLE
    Rodriguez-Villegas E, Chen G, Radcliffe J, Duncan Jet al., 2014,

    A pilot study of a wearable apnoea detection device

    , BMJ OPEN, Vol: 4, ISSN: 2044-6055
  • JOURNAL ARTICLE
    Rodriguez-Villegas E, Logesparan L, Casson AJ, 2014,

    A Low Power Linear Phase Programmable Long Delay Circuit

    , IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, Vol: 8, Pages: 432-441, ISSN: 1932-4545
  • JOURNAL ARTICLE
    Saraswat R, Rodriguez-Villegas E, 2014,

    Low Power EMI Mitigation Strategies Utilizing Non-PLL Based Periodic and Chaotic SSC Profiles for Implanted Devices

    , 2014 8TH INTERNATIONAL SYMPOSIUM ON MEDICAL INFORMATION AND COMMUNICATION TECHNOLOGY (ISMICT), ISSN: 2326-828X
  • CONFERENCE PAPER
    Saraswat R, Rodriguez-Villegas E, 2014,

    Chaotic Inductively Coupled Non-PLL Low Emission Transmitter for Implanted Devices

    , IEEE 5th Latin American Symposium on Circuits and Systems (LASCAS), Publisher: IEEE, ISSN: 2330-9954
  • CONFERENCE PAPER
    Imtiaz SA, Saremi-Yarahmadi S, Rodriguez-Villegas E, 2013,

    Automatic detection of sleep spindles using Teager energy and spectral edge frequency

    , IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 262-265

    Sleep spindles are the hallmark of N2 stage of sleep. They are transient waveforms observed on sleep electroencephalogram and their identification is required for sleep staging. Due to the large number of sleep spindles appearing on an overnight sleep EEG, automating the detection of sleep spindles would be desirable, not only to save specialist time but also for fully automated sleep staging systems. A simple algorithm for automatic sleep spindle detection is presented in this paper using only one channel of EEG input. This algorithm uses Teager energy and spectral edge frequency to mark sleep spindles and results in a sensitivity of 80% and specificity of about 98%. It is also shown that more than 91% of spindles detected by the algorithm were in N2 and N3 stages combined.

  • JOURNAL ARTICLE
    Kafali O, Bromuri S, Sindlar M, van der Weide T, Pelaez EA, Schaechtle U, Alves B, Zufferey D, Rodriguez-Villegas E, Schumacher MI, Stathis Ket al., 2013,

    COMMODITY12: A smart e-health environment for diabetes management

    , JOURNAL OF AMBIENT INTELLIGENCE AND SMART ENVIRONMENTS, Vol: 5, Pages: 479-502, ISSN: 1876-1364
  • CONFERENCE PAPER
    Logesparan L, Casson AJ, Imtiaz SA, Rodriguez-Villegas Eet al., 2013,

    Discriminating between best performing features for seizure detection and data selection

    , 35th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC), Publisher: IEEE, Pages: 1692-1695, ISSN: 1557-170X
  • JOURNAL ARTICLE
    Pinuela M, Yates DC, Lucyszyn S, Mitcheson PDet al., 2013,

    Maximizing DC-to-Load Efficiency for Inductive Power Transfer

    , IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 28, Pages: 2437-2447, ISSN: 0885-8993
  • CONFERENCE PAPER
    Rajagopal MK, Rodriguez-Villegas E, 2013,

    Towards Wearable Sleep Diagnostic Systems for Point-of-Care Applications

    , 1st IEEE-EMBS Special Topic Conference on Point-of-Care (POCT) Healthcare Technologies (PHT), Publisher: IEEE, Pages: 26-29
  • CONFERENCE PAPER
    Saraswat R, Rodriguez-Villegas E, 2013,

    A Low Emission, Low Power Non-Linear Frequency Modulation Based Transmitter For Implanted Devices

    , 35th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC), Publisher: IEEE, Pages: 826-829, ISSN: 1557-170X
  • JOURNAL ARTICLE
    Abdulghani AM, Casson AJ, Rodriguez-Villegas E, 2012,

    Compressive sensing scalp EEG signals: implementations and practical performance

    , MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING, Vol: 50, Pages: 1137-1145, ISSN: 0140-0118
  • JOURNAL ARTICLE
    Aguilar-Pelaez E, Chen G, Rodriguez-Villegas E, 2012,

    Technique for Interference Reduction in Battery Powered Physiological Monitoring Devices

    , IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 59, Pages: 3197-3203, ISSN: 0018-9294
  • CONFERENCE PAPER
    Casson AJ, Rodriguez-Villegas E, 2012,

    Signal agnostic compressive sensing for Body Area Networks: Comparison of signal reconstructions

    , 34th Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBS), Publisher: IEEE, Pages: 4497-4500, ISSN: 1557-170X
  • CONFERENCE PAPER
    Hizon JRE, Rodriguez-Villegas E, 2012,

    A Compact Linearly Tunable Low Voltage Triode OTA Using Self-Cascodes

    , IEEE International Symposium on Circuits and Systems, Publisher: IEEE, Pages: 440-443, ISSN: 0271-4302
  • CONFERENCE PAPER
    Hizon JRE, Rodriguez-Villegas E, 2012,

    A High Transconductance Efficiency FGMOS OTA for g(m)-C Ladder Filters

    , 55th IEEE International Midwest Symposium on Circuits and Systems (MWSCAS), Publisher: IEEE, Pages: 105-108, ISSN: 1548-3746
  • JOURNAL ARTICLE
    Logesparan L, Casson AJ, Rodriguez-Villegas E, 2012,

    Optimal features for online seizure detection

    , MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING, Vol: 50, Pages: 659-669, ISSN: 0140-0118
  • CONFERENCE PAPER
    Logesparan L, Casson AJ, Rodriguez-Villegas E, 2012,

    Improving seizure detection performance reporting: analysing the duration needed for a detection

    , 34th Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBS), Publisher: IEEE, Pages: 1069-1072, ISSN: 1557-170X
  • CONFERENCE PAPER
    Mardell J, Witkowski M, Spence R, 2012,

    An Interface for Visual Inspection based on Image Segmentation

    , International Working Conference on Advanced Visual Interfaces (AVI), Publisher: ASSOC COMPUTING MACHINERY, Pages: 697-700
  • PATENT
    Rodriguez-Villegas E, 2012,

    Feature characterization for breathing monitor

  • JOURNAL ARTICLE
    Shad A, Rodriguez-Villegas E, 2012,

    Proof of concept of a shoe based human activity monitor.

    , Conf Proc IEEE Eng Med Biol Soc, Vol: 2012, Pages: 6398-6401, ISSN: 1557-170X

    This paper presents the proof of concept of a low power, low cost, wearable activity monitor. The functionality of the system is based on accurate stride detection from signals generated by two force sensing resistors integrated within a normal shoe. A novel algorithm is proposed that is able to differentiate between walking and non-walking activities with high accuracy. The performance of the proof of concept system was validated in five subjects who underwent five repetitions of three different speed walking tests, and five repetitions of five non-walking artefact generating tests. The system achieved a total sensitivity of 96% with 98% specificity and an overall accuracy of 94%.

  • CONFERENCE PAPER
    Brinded T, Mardell J, Witkowski M, Spence Ret al., 2011,

    The Effects of Image Speed and Overlap on Image Recognition.

    , Publisher: IEEE Computer Society, Pages: 3-11
  • JOURNAL ARTICLE
    Casson AJ, Rodriguez-Villegas E, 2011,

    A 60 pW g(m)C Continuous Wavelet Transform Circuit for Portable EEG Systems

    , IEEE JOURNAL OF SOLID-STATE CIRCUITS, Vol: 46, Pages: 1406-1415, ISSN: 0018-9200
  • JOURNAL ARTICLE
    Casson AJ, Rodriguez-Villegas E, 2011,

    Utilising noise to improve an interictal spike detector

    , JOURNAL OF NEUROSCIENCE METHODS, Vol: 201, Pages: 262-268, ISSN: 0165-0270
  • JOURNAL ARTICLE
    Casson AJ, Rodriguez-Villegas E, 2011,

    "A review and modern approach to LC ladder synthesis,"

    , Journal of Low Power Electronics and Applications, Vol: 1, Pages: 20-44
  • BOOK CHAPTER
    Casson AJ, Rodriguez-Villegas E, 2011,

    Interfacing Biology and Circuits: Quantification and Performance Metrics

    , CMOS Biomicrosystems: Where Electronics Meet Biology, Pages: 1-32, ISBN: 9780470641903
  • CONFERENCE PAPER
    Casson AJ, Rodriguez-Villegas E, 2011,

    Algorithms and circuits for truly wearable physiological monitoring

    , 33rd international conference of the IEEE Engineering in Medicine and Biology Society
  • JOURNAL ARTICLE
    He C, Kiziroglou ME, Yates DC, 2011,

    A MEMS Self-Powered Sensor and RF Transmission Platform for WSN Nodes

    , IEEE Sensors Journal, Vol: 11, Pages: 3437-3445
  • JOURNAL ARTICLE
    He C, Kiziroglou ME, Yates DC, Yeatman EMet al., 2011,

    A MEMS Self-Powered Sensor and RF Transmission Platform for WSN Nodes

    , IEEE SENSORS JOURNAL, Vol: 11, Pages: 3437-3445, ISSN: 1530-437X
  • CONFERENCE PAPER
    Logesparan L, Casson AJ, Rodriguez-Villegas E, 2011,

    Performance metrics for characterization of a seizure detection algorithm for offline and online use

    , 5th International Workshop on Seizure Prediction

    Purpose: To select appropriate previously reported performance metrics to evaluate a new seizure detection algorithm for offline and online analysis, and thus quantify any performance variation between these metrics.Methods: Traditional offline algorithms mark out any EEG section (epoch) of a seizure (event), so that neurologists only analyze the detected and adjacent sections. Thus, offline algorithms could be evaluated using number of correctly detected events, or event-based sensitivity (SEVENT), and epoch-based specificity (percentage of incorrectly detected background epochs). In contrast, online seizure detection (especially, data selection) algorithms select for transmission only the detected EEG sections and hence need to detect the entire duration of a seizure. Thus, online algorithms could be evaluated using percentage of correctly detected seizure duration, or epoch-based sensitivity (SEPOCH), and epoch-based specificity. Here, a new seizure detection algorithm is evaluated using the selected performance metrics for epoch duration ranging from 1s to 60s.Results: For 1s epochs, the area under the event-based sensitivity-specificity curve was 0.95 whilst SEPOCH achieves 0.81. This difference is not surprising, as intuitively, detecting any epoch within a seizure is easier than detecting every epoch - especially as seizures evolve over time. For longer epochs of 30s or 60s, SEVENT falls to 0.84 and 0.82 respectively and SEPOCH reduces to 0.76. Here, decreased SEVENT shows that fewer seizures are detected, possibly due to easy-to-detect short seizure sections being masked by surrounding EEG. However, detecting one long epoch constitutes a larger percentage of a seizure than a shorter one and thus SEPOCH does not decrease proportionately.Conclusions: Traditional offline and online seizure detection algorithms require different metrics to effectively evaluate their performance for their respective applications. Using such metrics, it has been shown that a decre

  • CONFERENCE PAPER
    Logesparan L, Casson AJ, Rodriguez-Villegas E, 2011,

    Assessing the impact of signal normalization: preliminary results on epileptic seizure detection

    , 33rd Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBS), Publisher: IEEE, Pages: 1439-1442, ISSN: 1557-170X
  • JOURNAL ARTICLE
    Logesparan L, Rodriguez-Villegas E, 2011,

    A Novel Phase Congruency Based Algorithm for Online Data Reduction in Ambulatory EEG Systems

    , IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 58, Pages: 2825-2834, ISSN: 0018-9294
  • CONFERENCE PAPER
    Mardell J, Witkowski M, Spence R, 2011,

    Gaze-contingent enhancements for a visual search and rescue task.

    , Publisher: ACM, Pages: 109-109
  • JOURNAL ARTICLE
    Rodriguez-Villegas E, Casson AJ, Corbishley P, 2011,

    A Subhertz Nanopower Low-Pass Filter

    , IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS, Vol: 58, Pages: 351-355, ISSN: 1549-7747
  • CONFERENCE PAPER
    Saremi-Yarahmadi S, Fobelets K, Toumazou C, 2011,

    Coupled Inductive Sensors for Monitoring the pH of Electrolyte Solutions

    , IEEE International Conference on Dielectric Liquids (ICDL), Publisher: IEEE
  • CONFERENCE PAPER
    Saremi-Yarahmadi S, Fobelets K, Toumazou C, 2011,

    Coupled RF inductive sensors for monitoring the conductivity of electrolyte solutions

    , Pages: 20-23

    The use of closely coupled inductors, operating in the region of 10 MHz to 1 GHz, for detection of change in the concentration of ionic species present in a liquid sample, is reported here. The S-parameters were measured for the coupled inductors with liquid samples under varying pH conditions on one inductor only. S12 parameters were used as an indicator for the coupling between the two inductors. The results from this study show that coupled coil systems can be employed in simple sensing systems to monitor electrolyte solutions without the need for direct physical contact to the sensor itself. This design has the potential of being used for applications such as monitoring DNA hybridization or monitoring the conductance of electrolyte solutions with high conductivity while simplifying packaging steps required. © 2011 IEEE.

  • CONFERENCE PAPER
    Abdulghani AM, Casson AJ, Rodriguez-Villegas E, 2010,

    Quantifying the performance of compressive sensing on scalp EEG signals

    Compressive sensing is a new data compression paradigm that has shown significant promise in fields such as MRI. However, the practical performance of the theory very much depends on the characteristics of the signal being sensed. As such the utility of the technique cannot be extrapolated from one application to another. Electroencephalography (EEG) is a fundamental tool for the investigation of many neurological disorders and is increasingly also used in many non-medical applications, such as Brain-Computer Interfaces. This paper characterises in detail the practical performance of different implementations of the compressive sensing theory when applied to scalp EEG signals for the first time. The results are of particular interest for wearable EEG communication systems requiring low power, real-time compression of the EEG data. ©2010 IEEE.

  • CONFERENCE PAPER
    Abdulghani AM, Rodriguez-Villegas E, 2010,

    Compressive Sensing: From "Compressing while Sampling" to "Compressing and Securing while Sampling"

    , 32nd Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBC 10), Publisher: IEEE, Pages: 1127-1130, ISSN: 1557-170X

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